With the evolution of photovoltaic and semiconductor technology, the flat panel display is also developing fast. Among various types of flat panel displays, the liquid crystal display (LCD) has become a spotlight in the market due to the superior characteristics, such as higher space utilization, lower power consumption, zero radiation, and lower electro-magnetic interference, and so on.
Currently, a-Si TFTs are widely used as the switch element of LCDs. However, the a-Si TFT LCD is still limited in terms of the various demands (such as thinner body, smaller weight, higher fineness, higher brightness, higher reliability, and lower power consumption, and so on). To satisfy the above demand, the lower temperature polycrystal silicon (LTPS) TFT LCD is apparently advantageous compared with the a-Si TFT LCD. However, current manufacturing process of the LTPS TFT is relatively complex, and at least eight masks are required to form the LTPS TFT.
The processes for forming the LTPS TFT array substrate with either maksts in the prior art sequentially include: p-Si patterning, specifically referring to forming a polycrystal silicon pattern after a p-Si dry etch; shielding a P-type area, and conducting ion implantation on a N-type area (source/drain); performing gate deposition, forming a first metal layer, and defining a gate; shielding the N-type area, and conducting ion implantation on the P-type area; forming contact holes; depositing a wiring layer, forming a second metal layer, and defining data line pattern; depositing a flat layer, and forming contact holes; defining the shape of a pixel electrode. The processes of forming the LTPS TFT array substrate in the prior art are very complex, which is disadvantageous in lowering the cost.